Root/
1 | /* |
2 | * Linux Magic System Request Key Hacks |
3 | * |
4 | * (c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz> |
5 | * based on ideas by Pavel Machek <pavel@atrey.karlin.mff.cuni.cz> |
6 | * |
7 | * (c) 2000 Crutcher Dunnavant <crutcher+kernel@datastacks.com> |
8 | * overhauled to use key registration |
9 | * based upon discusions in irc://irc.openprojects.net/#kernelnewbies |
10 | * |
11 | * Copyright (c) 2010 Dmitry Torokhov |
12 | * Input handler conversion |
13 | */ |
14 | |
15 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
16 | |
17 | #include <linux/sched.h> |
18 | #include <linux/sched/rt.h> |
19 | #include <linux/interrupt.h> |
20 | #include <linux/mm.h> |
21 | #include <linux/fs.h> |
22 | #include <linux/mount.h> |
23 | #include <linux/kdev_t.h> |
24 | #include <linux/major.h> |
25 | #include <linux/reboot.h> |
26 | #include <linux/sysrq.h> |
27 | #include <linux/kbd_kern.h> |
28 | #include <linux/proc_fs.h> |
29 | #include <linux/nmi.h> |
30 | #include <linux/quotaops.h> |
31 | #include <linux/perf_event.h> |
32 | #include <linux/kernel.h> |
33 | #include <linux/module.h> |
34 | #include <linux/suspend.h> |
35 | #include <linux/writeback.h> |
36 | #include <linux/swap.h> |
37 | #include <linux/spinlock.h> |
38 | #include <linux/vt_kern.h> |
39 | #include <linux/workqueue.h> |
40 | #include <linux/hrtimer.h> |
41 | #include <linux/oom.h> |
42 | #include <linux/slab.h> |
43 | #include <linux/input.h> |
44 | #include <linux/uaccess.h> |
45 | #include <linux/moduleparam.h> |
46 | |
47 | #include <asm/ptrace.h> |
48 | #include <asm/irq_regs.h> |
49 | |
50 | /* Whether we react on sysrq keys or just ignore them */ |
51 | static int __read_mostly sysrq_enabled = SYSRQ_DEFAULT_ENABLE; |
52 | static bool __read_mostly sysrq_always_enabled; |
53 | |
54 | static bool sysrq_on(void) |
55 | { |
56 | return sysrq_enabled || sysrq_always_enabled; |
57 | } |
58 | |
59 | /* |
60 | * A value of 1 means 'all', other nonzero values are an op mask: |
61 | */ |
62 | static bool sysrq_on_mask(int mask) |
63 | { |
64 | return sysrq_always_enabled || |
65 | sysrq_enabled == 1 || |
66 | (sysrq_enabled & mask); |
67 | } |
68 | |
69 | static int __init sysrq_always_enabled_setup(char *str) |
70 | { |
71 | sysrq_always_enabled = true; |
72 | pr_info("sysrq always enabled.\n"); |
73 | |
74 | return 1; |
75 | } |
76 | |
77 | __setup("sysrq_always_enabled", sysrq_always_enabled_setup); |
78 | |
79 | |
80 | static void sysrq_handle_loglevel(int key) |
81 | { |
82 | int i; |
83 | |
84 | i = key - '0'; |
85 | console_loglevel = 7; |
86 | printk("Loglevel set to %d\n", i); |
87 | console_loglevel = i; |
88 | } |
89 | static struct sysrq_key_op sysrq_loglevel_op = { |
90 | .handler = sysrq_handle_loglevel, |
91 | .help_msg = "loglevel(0-9)", |
92 | .action_msg = "Changing Loglevel", |
93 | .enable_mask = SYSRQ_ENABLE_LOG, |
94 | }; |
95 | |
96 | #ifdef CONFIG_VT |
97 | static void sysrq_handle_SAK(int key) |
98 | { |
99 | struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work; |
100 | schedule_work(SAK_work); |
101 | } |
102 | static struct sysrq_key_op sysrq_SAK_op = { |
103 | .handler = sysrq_handle_SAK, |
104 | .help_msg = "saK", |
105 | .action_msg = "SAK", |
106 | .enable_mask = SYSRQ_ENABLE_KEYBOARD, |
107 | }; |
108 | #else |
109 | #define sysrq_SAK_op (*(struct sysrq_key_op *)NULL) |
110 | #endif |
111 | |
112 | #ifdef CONFIG_VT |
113 | static void sysrq_handle_unraw(int key) |
114 | { |
115 | vt_reset_unicode(fg_console); |
116 | } |
117 | |
118 | static struct sysrq_key_op sysrq_unraw_op = { |
119 | .handler = sysrq_handle_unraw, |
120 | .help_msg = "unRaw", |
121 | .action_msg = "Keyboard mode set to system default", |
122 | .enable_mask = SYSRQ_ENABLE_KEYBOARD, |
123 | }; |
124 | #else |
125 | #define sysrq_unraw_op (*(struct sysrq_key_op *)NULL) |
126 | #endif /* CONFIG_VT */ |
127 | |
128 | static void sysrq_handle_crash(int key) |
129 | { |
130 | char *killer = NULL; |
131 | |
132 | panic_on_oops = 1; /* force panic */ |
133 | wmb(); |
134 | *killer = 1; |
135 | } |
136 | static struct sysrq_key_op sysrq_crash_op = { |
137 | .handler = sysrq_handle_crash, |
138 | .help_msg = "Crash", |
139 | .action_msg = "Trigger a crash", |
140 | .enable_mask = SYSRQ_ENABLE_DUMP, |
141 | }; |
142 | |
143 | static void sysrq_handle_reboot(int key) |
144 | { |
145 | lockdep_off(); |
146 | local_irq_enable(); |
147 | emergency_restart(); |
148 | } |
149 | static struct sysrq_key_op sysrq_reboot_op = { |
150 | .handler = sysrq_handle_reboot, |
151 | .help_msg = "reBoot", |
152 | .action_msg = "Resetting", |
153 | .enable_mask = SYSRQ_ENABLE_BOOT, |
154 | }; |
155 | |
156 | static void sysrq_handle_sync(int key) |
157 | { |
158 | emergency_sync(); |
159 | } |
160 | static struct sysrq_key_op sysrq_sync_op = { |
161 | .handler = sysrq_handle_sync, |
162 | .help_msg = "Sync", |
163 | .action_msg = "Emergency Sync", |
164 | .enable_mask = SYSRQ_ENABLE_SYNC, |
165 | }; |
166 | |
167 | static void sysrq_handle_show_timers(int key) |
168 | { |
169 | sysrq_timer_list_show(); |
170 | } |
171 | |
172 | static struct sysrq_key_op sysrq_show_timers_op = { |
173 | .handler = sysrq_handle_show_timers, |
174 | .help_msg = "show-all-timers(Q)", |
175 | .action_msg = "Show clockevent devices & pending hrtimers (no others)", |
176 | }; |
177 | |
178 | static void sysrq_handle_mountro(int key) |
179 | { |
180 | emergency_remount(); |
181 | } |
182 | static struct sysrq_key_op sysrq_mountro_op = { |
183 | .handler = sysrq_handle_mountro, |
184 | .help_msg = "Unmount", |
185 | .action_msg = "Emergency Remount R/O", |
186 | .enable_mask = SYSRQ_ENABLE_REMOUNT, |
187 | }; |
188 | |
189 | #ifdef CONFIG_LOCKDEP |
190 | static void sysrq_handle_showlocks(int key) |
191 | { |
192 | debug_show_all_locks(); |
193 | } |
194 | |
195 | static struct sysrq_key_op sysrq_showlocks_op = { |
196 | .handler = sysrq_handle_showlocks, |
197 | .help_msg = "show-all-locks(D)", |
198 | .action_msg = "Show Locks Held", |
199 | }; |
200 | #else |
201 | #define sysrq_showlocks_op (*(struct sysrq_key_op *)NULL) |
202 | #endif |
203 | |
204 | #ifdef CONFIG_SMP |
205 | static DEFINE_SPINLOCK(show_lock); |
206 | |
207 | static void showacpu(void *dummy) |
208 | { |
209 | unsigned long flags; |
210 | |
211 | /* Idle CPUs have no interesting backtrace. */ |
212 | if (idle_cpu(smp_processor_id())) |
213 | return; |
214 | |
215 | spin_lock_irqsave(&show_lock, flags); |
216 | printk(KERN_INFO "CPU%d:\n", smp_processor_id()); |
217 | show_stack(NULL, NULL); |
218 | spin_unlock_irqrestore(&show_lock, flags); |
219 | } |
220 | |
221 | static void sysrq_showregs_othercpus(struct work_struct *dummy) |
222 | { |
223 | smp_call_function(showacpu, NULL, 0); |
224 | } |
225 | |
226 | static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus); |
227 | |
228 | static void sysrq_handle_showallcpus(int key) |
229 | { |
230 | /* |
231 | * Fall back to the workqueue based printing if the |
232 | * backtrace printing did not succeed or the |
233 | * architecture has no support for it: |
234 | */ |
235 | if (!trigger_all_cpu_backtrace()) { |
236 | struct pt_regs *regs = get_irq_regs(); |
237 | |
238 | if (regs) { |
239 | printk(KERN_INFO "CPU%d:\n", smp_processor_id()); |
240 | show_regs(regs); |
241 | } |
242 | schedule_work(&sysrq_showallcpus); |
243 | } |
244 | } |
245 | |
246 | static struct sysrq_key_op sysrq_showallcpus_op = { |
247 | .handler = sysrq_handle_showallcpus, |
248 | .help_msg = "show-backtrace-all-active-cpus(L)", |
249 | .action_msg = "Show backtrace of all active CPUs", |
250 | .enable_mask = SYSRQ_ENABLE_DUMP, |
251 | }; |
252 | #endif |
253 | |
254 | static void sysrq_handle_showregs(int key) |
255 | { |
256 | struct pt_regs *regs = get_irq_regs(); |
257 | if (regs) |
258 | show_regs(regs); |
259 | perf_event_print_debug(); |
260 | } |
261 | static struct sysrq_key_op sysrq_showregs_op = { |
262 | .handler = sysrq_handle_showregs, |
263 | .help_msg = "show-registers(P)", |
264 | .action_msg = "Show Regs", |
265 | .enable_mask = SYSRQ_ENABLE_DUMP, |
266 | }; |
267 | |
268 | static void sysrq_handle_showstate(int key) |
269 | { |
270 | show_state(); |
271 | } |
272 | static struct sysrq_key_op sysrq_showstate_op = { |
273 | .handler = sysrq_handle_showstate, |
274 | .help_msg = "show-task-states(T)", |
275 | .action_msg = "Show State", |
276 | .enable_mask = SYSRQ_ENABLE_DUMP, |
277 | }; |
278 | |
279 | static void sysrq_handle_showstate_blocked(int key) |
280 | { |
281 | show_state_filter(TASK_UNINTERRUPTIBLE); |
282 | } |
283 | static struct sysrq_key_op sysrq_showstate_blocked_op = { |
284 | .handler = sysrq_handle_showstate_blocked, |
285 | .help_msg = "show-blocked-tasks(W)", |
286 | .action_msg = "Show Blocked State", |
287 | .enable_mask = SYSRQ_ENABLE_DUMP, |
288 | }; |
289 | |
290 | #ifdef CONFIG_TRACING |
291 | #include <linux/ftrace.h> |
292 | |
293 | static void sysrq_ftrace_dump(int key) |
294 | { |
295 | ftrace_dump(DUMP_ALL); |
296 | } |
297 | static struct sysrq_key_op sysrq_ftrace_dump_op = { |
298 | .handler = sysrq_ftrace_dump, |
299 | .help_msg = "dump-ftrace-buffer(Z)", |
300 | .action_msg = "Dump ftrace buffer", |
301 | .enable_mask = SYSRQ_ENABLE_DUMP, |
302 | }; |
303 | #else |
304 | #define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL) |
305 | #endif |
306 | |
307 | static void sysrq_handle_showmem(int key) |
308 | { |
309 | show_mem(0); |
310 | } |
311 | static struct sysrq_key_op sysrq_showmem_op = { |
312 | .handler = sysrq_handle_showmem, |
313 | .help_msg = "show-memory-usage(M)", |
314 | .action_msg = "Show Memory", |
315 | .enable_mask = SYSRQ_ENABLE_DUMP, |
316 | }; |
317 | |
318 | /* |
319 | * Signal sysrq helper function. Sends a signal to all user processes. |
320 | */ |
321 | static void send_sig_all(int sig) |
322 | { |
323 | struct task_struct *p; |
324 | |
325 | read_lock(&tasklist_lock); |
326 | for_each_process(p) { |
327 | if (p->flags & PF_KTHREAD) |
328 | continue; |
329 | if (is_global_init(p)) |
330 | continue; |
331 | |
332 | do_send_sig_info(sig, SEND_SIG_FORCED, p, true); |
333 | } |
334 | read_unlock(&tasklist_lock); |
335 | } |
336 | |
337 | static void sysrq_handle_term(int key) |
338 | { |
339 | send_sig_all(SIGTERM); |
340 | console_loglevel = 8; |
341 | } |
342 | static struct sysrq_key_op sysrq_term_op = { |
343 | .handler = sysrq_handle_term, |
344 | .help_msg = "terminate-all-tasks(E)", |
345 | .action_msg = "Terminate All Tasks", |
346 | .enable_mask = SYSRQ_ENABLE_SIGNAL, |
347 | }; |
348 | |
349 | static void moom_callback(struct work_struct *ignored) |
350 | { |
351 | out_of_memory(node_zonelist(first_online_node, GFP_KERNEL), GFP_KERNEL, |
352 | 0, NULL, true); |
353 | } |
354 | |
355 | static DECLARE_WORK(moom_work, moom_callback); |
356 | |
357 | static void sysrq_handle_moom(int key) |
358 | { |
359 | schedule_work(&moom_work); |
360 | } |
361 | static struct sysrq_key_op sysrq_moom_op = { |
362 | .handler = sysrq_handle_moom, |
363 | .help_msg = "memory-full-oom-kill(F)", |
364 | .action_msg = "Manual OOM execution", |
365 | .enable_mask = SYSRQ_ENABLE_SIGNAL, |
366 | }; |
367 | |
368 | #ifdef CONFIG_BLOCK |
369 | static void sysrq_handle_thaw(int key) |
370 | { |
371 | emergency_thaw_all(); |
372 | } |
373 | static struct sysrq_key_op sysrq_thaw_op = { |
374 | .handler = sysrq_handle_thaw, |
375 | .help_msg = "thaw-filesystems(J)", |
376 | .action_msg = "Emergency Thaw of all frozen filesystems", |
377 | .enable_mask = SYSRQ_ENABLE_SIGNAL, |
378 | }; |
379 | #endif |
380 | |
381 | static void sysrq_handle_kill(int key) |
382 | { |
383 | send_sig_all(SIGKILL); |
384 | console_loglevel = 8; |
385 | } |
386 | static struct sysrq_key_op sysrq_kill_op = { |
387 | .handler = sysrq_handle_kill, |
388 | .help_msg = "kill-all-tasks(I)", |
389 | .action_msg = "Kill All Tasks", |
390 | .enable_mask = SYSRQ_ENABLE_SIGNAL, |
391 | }; |
392 | |
393 | static void sysrq_handle_unrt(int key) |
394 | { |
395 | normalize_rt_tasks(); |
396 | } |
397 | static struct sysrq_key_op sysrq_unrt_op = { |
398 | .handler = sysrq_handle_unrt, |
399 | .help_msg = "nice-all-RT-tasks(N)", |
400 | .action_msg = "Nice All RT Tasks", |
401 | .enable_mask = SYSRQ_ENABLE_RTNICE, |
402 | }; |
403 | |
404 | /* Key Operations table and lock */ |
405 | static DEFINE_SPINLOCK(sysrq_key_table_lock); |
406 | |
407 | static struct sysrq_key_op *sysrq_key_table[36] = { |
408 | &sysrq_loglevel_op, /* 0 */ |
409 | &sysrq_loglevel_op, /* 1 */ |
410 | &sysrq_loglevel_op, /* 2 */ |
411 | &sysrq_loglevel_op, /* 3 */ |
412 | &sysrq_loglevel_op, /* 4 */ |
413 | &sysrq_loglevel_op, /* 5 */ |
414 | &sysrq_loglevel_op, /* 6 */ |
415 | &sysrq_loglevel_op, /* 7 */ |
416 | &sysrq_loglevel_op, /* 8 */ |
417 | &sysrq_loglevel_op, /* 9 */ |
418 | |
419 | /* |
420 | * a: Don't use for system provided sysrqs, it is handled specially on |
421 | * sparc and will never arrive. |
422 | */ |
423 | NULL, /* a */ |
424 | &sysrq_reboot_op, /* b */ |
425 | &sysrq_crash_op, /* c & ibm_emac driver debug */ |
426 | &sysrq_showlocks_op, /* d */ |
427 | &sysrq_term_op, /* e */ |
428 | &sysrq_moom_op, /* f */ |
429 | /* g: May be registered for the kernel debugger */ |
430 | NULL, /* g */ |
431 | NULL, /* h - reserved for help */ |
432 | &sysrq_kill_op, /* i */ |
433 | #ifdef CONFIG_BLOCK |
434 | &sysrq_thaw_op, /* j */ |
435 | #else |
436 | NULL, /* j */ |
437 | #endif |
438 | &sysrq_SAK_op, /* k */ |
439 | #ifdef CONFIG_SMP |
440 | &sysrq_showallcpus_op, /* l */ |
441 | #else |
442 | NULL, /* l */ |
443 | #endif |
444 | &sysrq_showmem_op, /* m */ |
445 | &sysrq_unrt_op, /* n */ |
446 | /* o: This will often be registered as 'Off' at init time */ |
447 | NULL, /* o */ |
448 | &sysrq_showregs_op, /* p */ |
449 | &sysrq_show_timers_op, /* q */ |
450 | &sysrq_unraw_op, /* r */ |
451 | &sysrq_sync_op, /* s */ |
452 | &sysrq_showstate_op, /* t */ |
453 | &sysrq_mountro_op, /* u */ |
454 | /* v: May be registered for frame buffer console restore */ |
455 | NULL, /* v */ |
456 | &sysrq_showstate_blocked_op, /* w */ |
457 | /* x: May be registered on ppc/powerpc for xmon */ |
458 | /* x: May be registered on sparc64 for global PMU dump */ |
459 | NULL, /* x */ |
460 | /* y: May be registered on sparc64 for global register dump */ |
461 | NULL, /* y */ |
462 | &sysrq_ftrace_dump_op, /* z */ |
463 | }; |
464 | |
465 | /* key2index calculation, -1 on invalid index */ |
466 | static int sysrq_key_table_key2index(int key) |
467 | { |
468 | int retval; |
469 | |
470 | if ((key >= '0') && (key <= '9')) |
471 | retval = key - '0'; |
472 | else if ((key >= 'a') && (key <= 'z')) |
473 | retval = key + 10 - 'a'; |
474 | else |
475 | retval = -1; |
476 | return retval; |
477 | } |
478 | |
479 | /* |
480 | * get and put functions for the table, exposed to modules. |
481 | */ |
482 | struct sysrq_key_op *__sysrq_get_key_op(int key) |
483 | { |
484 | struct sysrq_key_op *op_p = NULL; |
485 | int i; |
486 | |
487 | i = sysrq_key_table_key2index(key); |
488 | if (i != -1) |
489 | op_p = sysrq_key_table[i]; |
490 | |
491 | return op_p; |
492 | } |
493 | |
494 | static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p) |
495 | { |
496 | int i = sysrq_key_table_key2index(key); |
497 | |
498 | if (i != -1) |
499 | sysrq_key_table[i] = op_p; |
500 | } |
501 | |
502 | void __handle_sysrq(int key, bool check_mask) |
503 | { |
504 | struct sysrq_key_op *op_p; |
505 | int orig_log_level; |
506 | int i; |
507 | unsigned long flags; |
508 | |
509 | spin_lock_irqsave(&sysrq_key_table_lock, flags); |
510 | /* |
511 | * Raise the apparent loglevel to maximum so that the sysrq header |
512 | * is shown to provide the user with positive feedback. We do not |
513 | * simply emit this at KERN_EMERG as that would change message |
514 | * routing in the consumers of /proc/kmsg. |
515 | */ |
516 | orig_log_level = console_loglevel; |
517 | console_loglevel = 7; |
518 | printk(KERN_INFO "SysRq : "); |
519 | |
520 | op_p = __sysrq_get_key_op(key); |
521 | if (op_p) { |
522 | /* |
523 | * Should we check for enabled operations (/proc/sysrq-trigger |
524 | * should not) and is the invoked operation enabled? |
525 | */ |
526 | if (!check_mask || sysrq_on_mask(op_p->enable_mask)) { |
527 | printk("%s\n", op_p->action_msg); |
528 | console_loglevel = orig_log_level; |
529 | op_p->handler(key); |
530 | } else { |
531 | printk("This sysrq operation is disabled.\n"); |
532 | } |
533 | } else { |
534 | printk("HELP : "); |
535 | /* Only print the help msg once per handler */ |
536 | for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) { |
537 | if (sysrq_key_table[i]) { |
538 | int j; |
539 | |
540 | for (j = 0; sysrq_key_table[i] != |
541 | sysrq_key_table[j]; j++) |
542 | ; |
543 | if (j != i) |
544 | continue; |
545 | printk("%s ", sysrq_key_table[i]->help_msg); |
546 | } |
547 | } |
548 | printk("\n"); |
549 | console_loglevel = orig_log_level; |
550 | } |
551 | spin_unlock_irqrestore(&sysrq_key_table_lock, flags); |
552 | } |
553 | |
554 | void handle_sysrq(int key) |
555 | { |
556 | if (sysrq_on()) |
557 | __handle_sysrq(key, true); |
558 | } |
559 | EXPORT_SYMBOL(handle_sysrq); |
560 | |
561 | #ifdef CONFIG_INPUT |
562 | |
563 | /* Simple translation table for the SysRq keys */ |
564 | static const unsigned char sysrq_xlate[KEY_CNT] = |
565 | "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */ |
566 | "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */ |
567 | "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */ |
568 | "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */ |
569 | "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */ |
570 | "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */ |
571 | "\r\000/"; /* 0x60 - 0x6f */ |
572 | |
573 | struct sysrq_state { |
574 | struct input_handle handle; |
575 | struct work_struct reinject_work; |
576 | unsigned long key_down[BITS_TO_LONGS(KEY_CNT)]; |
577 | unsigned int alt; |
578 | unsigned int alt_use; |
579 | bool active; |
580 | bool need_reinject; |
581 | bool reinjecting; |
582 | |
583 | /* reset sequence handling */ |
584 | bool reset_canceled; |
585 | unsigned long reset_keybit[BITS_TO_LONGS(KEY_CNT)]; |
586 | int reset_seq_len; |
587 | int reset_seq_cnt; |
588 | int reset_seq_version; |
589 | }; |
590 | |
591 | #define SYSRQ_KEY_RESET_MAX 20 /* Should be plenty */ |
592 | static unsigned short sysrq_reset_seq[SYSRQ_KEY_RESET_MAX]; |
593 | static unsigned int sysrq_reset_seq_len; |
594 | static unsigned int sysrq_reset_seq_version = 1; |
595 | |
596 | static void sysrq_parse_reset_sequence(struct sysrq_state *state) |
597 | { |
598 | int i; |
599 | unsigned short key; |
600 | |
601 | state->reset_seq_cnt = 0; |
602 | |
603 | for (i = 0; i < sysrq_reset_seq_len; i++) { |
604 | key = sysrq_reset_seq[i]; |
605 | |
606 | if (key == KEY_RESERVED || key > KEY_MAX) |
607 | break; |
608 | |
609 | __set_bit(key, state->reset_keybit); |
610 | state->reset_seq_len++; |
611 | |
612 | if (test_bit(key, state->key_down)) |
613 | state->reset_seq_cnt++; |
614 | } |
615 | |
616 | /* Disable reset until old keys are not released */ |
617 | state->reset_canceled = state->reset_seq_cnt != 0; |
618 | |
619 | state->reset_seq_version = sysrq_reset_seq_version; |
620 | } |
621 | |
622 | static bool sysrq_detect_reset_sequence(struct sysrq_state *state, |
623 | unsigned int code, int value) |
624 | { |
625 | if (!test_bit(code, state->reset_keybit)) { |
626 | /* |
627 | * Pressing any key _not_ in reset sequence cancels |
628 | * the reset sequence. |
629 | */ |
630 | if (value && state->reset_seq_cnt) |
631 | state->reset_canceled = true; |
632 | } else if (value == 0) { |
633 | /* key release */ |
634 | if (--state->reset_seq_cnt == 0) |
635 | state->reset_canceled = false; |
636 | } else if (value == 1) { |
637 | /* key press, not autorepeat */ |
638 | if (++state->reset_seq_cnt == state->reset_seq_len && |
639 | !state->reset_canceled) { |
640 | return true; |
641 | } |
642 | } |
643 | |
644 | return false; |
645 | } |
646 | |
647 | static void sysrq_reinject_alt_sysrq(struct work_struct *work) |
648 | { |
649 | struct sysrq_state *sysrq = |
650 | container_of(work, struct sysrq_state, reinject_work); |
651 | struct input_handle *handle = &sysrq->handle; |
652 | unsigned int alt_code = sysrq->alt_use; |
653 | |
654 | if (sysrq->need_reinject) { |
655 | /* we do not want the assignment to be reordered */ |
656 | sysrq->reinjecting = true; |
657 | mb(); |
658 | |
659 | /* Simulate press and release of Alt + SysRq */ |
660 | input_inject_event(handle, EV_KEY, alt_code, 1); |
661 | input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1); |
662 | input_inject_event(handle, EV_SYN, SYN_REPORT, 1); |
663 | |
664 | input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0); |
665 | input_inject_event(handle, EV_KEY, alt_code, 0); |
666 | input_inject_event(handle, EV_SYN, SYN_REPORT, 1); |
667 | |
668 | mb(); |
669 | sysrq->reinjecting = false; |
670 | } |
671 | } |
672 | |
673 | static bool sysrq_handle_keypress(struct sysrq_state *sysrq, |
674 | unsigned int code, int value) |
675 | { |
676 | bool was_active = sysrq->active; |
677 | bool suppress; |
678 | |
679 | switch (code) { |
680 | |
681 | case KEY_LEFTALT: |
682 | case KEY_RIGHTALT: |
683 | if (!value) { |
684 | /* One of ALTs is being released */ |
685 | if (sysrq->active && code == sysrq->alt_use) |
686 | sysrq->active = false; |
687 | |
688 | sysrq->alt = KEY_RESERVED; |
689 | |
690 | } else if (value != 2) { |
691 | sysrq->alt = code; |
692 | sysrq->need_reinject = false; |
693 | } |
694 | break; |
695 | |
696 | case KEY_SYSRQ: |
697 | if (value == 1 && sysrq->alt != KEY_RESERVED) { |
698 | sysrq->active = true; |
699 | sysrq->alt_use = sysrq->alt; |
700 | /* |
701 | * If nothing else will be pressed we'll need |
702 | * to re-inject Alt-SysRq keysroke. |
703 | */ |
704 | sysrq->need_reinject = true; |
705 | } |
706 | |
707 | /* |
708 | * Pretend that sysrq was never pressed at all. This |
709 | * is needed to properly handle KGDB which will try |
710 | * to release all keys after exiting debugger. If we |
711 | * do not clear key bit it KGDB will end up sending |
712 | * release events for Alt and SysRq, potentially |
713 | * triggering print screen function. |
714 | */ |
715 | if (sysrq->active) |
716 | clear_bit(KEY_SYSRQ, sysrq->handle.dev->key); |
717 | |
718 | break; |
719 | |
720 | default: |
721 | if (sysrq->active && value && value != 2) { |
722 | sysrq->need_reinject = false; |
723 | __handle_sysrq(sysrq_xlate[code], true); |
724 | } |
725 | break; |
726 | } |
727 | |
728 | suppress = sysrq->active; |
729 | |
730 | if (!sysrq->active) { |
731 | |
732 | /* |
733 | * See if reset sequence has changed since the last time. |
734 | */ |
735 | if (sysrq->reset_seq_version != sysrq_reset_seq_version) |
736 | sysrq_parse_reset_sequence(sysrq); |
737 | |
738 | /* |
739 | * If we are not suppressing key presses keep track of |
740 | * keyboard state so we can release keys that have been |
741 | * pressed before entering SysRq mode. |
742 | */ |
743 | if (value) |
744 | set_bit(code, sysrq->key_down); |
745 | else |
746 | clear_bit(code, sysrq->key_down); |
747 | |
748 | if (was_active) |
749 | schedule_work(&sysrq->reinject_work); |
750 | |
751 | if (sysrq_detect_reset_sequence(sysrq, code, value)) { |
752 | /* Force emergency reboot */ |
753 | __handle_sysrq(sysrq_xlate[KEY_B], false); |
754 | } |
755 | |
756 | } else if (value == 0 && test_and_clear_bit(code, sysrq->key_down)) { |
757 | /* |
758 | * Pass on release events for keys that was pressed before |
759 | * entering SysRq mode. |
760 | */ |
761 | suppress = false; |
762 | } |
763 | |
764 | return suppress; |
765 | } |
766 | |
767 | static bool sysrq_filter(struct input_handle *handle, |
768 | unsigned int type, unsigned int code, int value) |
769 | { |
770 | struct sysrq_state *sysrq = handle->private; |
771 | bool suppress; |
772 | |
773 | /* |
774 | * Do not filter anything if we are in the process of re-injecting |
775 | * Alt+SysRq combination. |
776 | */ |
777 | if (sysrq->reinjecting) |
778 | return false; |
779 | |
780 | switch (type) { |
781 | |
782 | case EV_SYN: |
783 | suppress = false; |
784 | break; |
785 | |
786 | case EV_KEY: |
787 | suppress = sysrq_handle_keypress(sysrq, code, value); |
788 | break; |
789 | |
790 | default: |
791 | suppress = sysrq->active; |
792 | break; |
793 | } |
794 | |
795 | return suppress; |
796 | } |
797 | |
798 | static int sysrq_connect(struct input_handler *handler, |
799 | struct input_dev *dev, |
800 | const struct input_device_id *id) |
801 | { |
802 | struct sysrq_state *sysrq; |
803 | int error; |
804 | |
805 | sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL); |
806 | if (!sysrq) |
807 | return -ENOMEM; |
808 | |
809 | INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq); |
810 | |
811 | sysrq->handle.dev = dev; |
812 | sysrq->handle.handler = handler; |
813 | sysrq->handle.name = "sysrq"; |
814 | sysrq->handle.private = sysrq; |
815 | |
816 | error = input_register_handle(&sysrq->handle); |
817 | if (error) { |
818 | pr_err("Failed to register input sysrq handler, error %d\n", |
819 | error); |
820 | goto err_free; |
821 | } |
822 | |
823 | error = input_open_device(&sysrq->handle); |
824 | if (error) { |
825 | pr_err("Failed to open input device, error %d\n", error); |
826 | goto err_unregister; |
827 | } |
828 | |
829 | return 0; |
830 | |
831 | err_unregister: |
832 | input_unregister_handle(&sysrq->handle); |
833 | err_free: |
834 | kfree(sysrq); |
835 | return error; |
836 | } |
837 | |
838 | static void sysrq_disconnect(struct input_handle *handle) |
839 | { |
840 | struct sysrq_state *sysrq = handle->private; |
841 | |
842 | input_close_device(handle); |
843 | cancel_work_sync(&sysrq->reinject_work); |
844 | input_unregister_handle(handle); |
845 | kfree(sysrq); |
846 | } |
847 | |
848 | /* |
849 | * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all |
850 | * keyboards have SysRq key predefined and so user may add it to keymap |
851 | * later, but we expect all such keyboards to have left alt. |
852 | */ |
853 | static const struct input_device_id sysrq_ids[] = { |
854 | { |
855 | .flags = INPUT_DEVICE_ID_MATCH_EVBIT | |
856 | INPUT_DEVICE_ID_MATCH_KEYBIT, |
857 | .evbit = { BIT_MASK(EV_KEY) }, |
858 | .keybit = { BIT_MASK(KEY_LEFTALT) }, |
859 | }, |
860 | { }, |
861 | }; |
862 | |
863 | static struct input_handler sysrq_handler = { |
864 | .filter = sysrq_filter, |
865 | .connect = sysrq_connect, |
866 | .disconnect = sysrq_disconnect, |
867 | .name = "sysrq", |
868 | .id_table = sysrq_ids, |
869 | }; |
870 | |
871 | static bool sysrq_handler_registered; |
872 | |
873 | unsigned short platform_sysrq_reset_seq[] __weak = { KEY_RESERVED }; |
874 | |
875 | static inline void sysrq_register_handler(void) |
876 | { |
877 | unsigned short key; |
878 | int error; |
879 | int i; |
880 | |
881 | for (i = 0; i < ARRAY_SIZE(sysrq_reset_seq); i++) { |
882 | key = platform_sysrq_reset_seq[i]; |
883 | if (key == KEY_RESERVED || key > KEY_MAX) |
884 | break; |
885 | |
886 | sysrq_reset_seq[sysrq_reset_seq_len++] = key; |
887 | } |
888 | |
889 | error = input_register_handler(&sysrq_handler); |
890 | if (error) |
891 | pr_err("Failed to register input handler, error %d", error); |
892 | else |
893 | sysrq_handler_registered = true; |
894 | } |
895 | |
896 | static inline void sysrq_unregister_handler(void) |
897 | { |
898 | if (sysrq_handler_registered) { |
899 | input_unregister_handler(&sysrq_handler); |
900 | sysrq_handler_registered = false; |
901 | } |
902 | } |
903 | |
904 | static int sysrq_reset_seq_param_set(const char *buffer, |
905 | const struct kernel_param *kp) |
906 | { |
907 | unsigned long val; |
908 | int error; |
909 | |
910 | error = strict_strtoul(buffer, 0, &val); |
911 | if (error < 0) |
912 | return error; |
913 | |
914 | if (val > KEY_MAX) |
915 | return -EINVAL; |
916 | |
917 | *((unsigned short *)kp->arg) = val; |
918 | sysrq_reset_seq_version++; |
919 | |
920 | return 0; |
921 | } |
922 | |
923 | static struct kernel_param_ops param_ops_sysrq_reset_seq = { |
924 | .get = param_get_ushort, |
925 | .set = sysrq_reset_seq_param_set, |
926 | }; |
927 | |
928 | #define param_check_sysrq_reset_seq(name, p) \ |
929 | __param_check(name, p, unsigned short) |
930 | |
931 | module_param_array_named(reset_seq, sysrq_reset_seq, sysrq_reset_seq, |
932 | &sysrq_reset_seq_len, 0644); |
933 | |
934 | #else |
935 | |
936 | static inline void sysrq_register_handler(void) |
937 | { |
938 | } |
939 | |
940 | static inline void sysrq_unregister_handler(void) |
941 | { |
942 | } |
943 | |
944 | #endif /* CONFIG_INPUT */ |
945 | |
946 | int sysrq_toggle_support(int enable_mask) |
947 | { |
948 | bool was_enabled = sysrq_on(); |
949 | |
950 | sysrq_enabled = enable_mask; |
951 | |
952 | if (was_enabled != sysrq_on()) { |
953 | if (sysrq_on()) |
954 | sysrq_register_handler(); |
955 | else |
956 | sysrq_unregister_handler(); |
957 | } |
958 | |
959 | return 0; |
960 | } |
961 | |
962 | static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p, |
963 | struct sysrq_key_op *remove_op_p) |
964 | { |
965 | int retval; |
966 | unsigned long flags; |
967 | |
968 | spin_lock_irqsave(&sysrq_key_table_lock, flags); |
969 | if (__sysrq_get_key_op(key) == remove_op_p) { |
970 | __sysrq_put_key_op(key, insert_op_p); |
971 | retval = 0; |
972 | } else { |
973 | retval = -1; |
974 | } |
975 | spin_unlock_irqrestore(&sysrq_key_table_lock, flags); |
976 | return retval; |
977 | } |
978 | |
979 | int register_sysrq_key(int key, struct sysrq_key_op *op_p) |
980 | { |
981 | return __sysrq_swap_key_ops(key, op_p, NULL); |
982 | } |
983 | EXPORT_SYMBOL(register_sysrq_key); |
984 | |
985 | int unregister_sysrq_key(int key, struct sysrq_key_op *op_p) |
986 | { |
987 | return __sysrq_swap_key_ops(key, NULL, op_p); |
988 | } |
989 | EXPORT_SYMBOL(unregister_sysrq_key); |
990 | |
991 | #ifdef CONFIG_PROC_FS |
992 | /* |
993 | * writing 'C' to /proc/sysrq-trigger is like sysrq-C |
994 | */ |
995 | static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf, |
996 | size_t count, loff_t *ppos) |
997 | { |
998 | if (count) { |
999 | char c; |
1000 | |
1001 | if (get_user(c, buf)) |
1002 | return -EFAULT; |
1003 | __handle_sysrq(c, false); |
1004 | } |
1005 | |
1006 | return count; |
1007 | } |
1008 | |
1009 | static const struct file_operations proc_sysrq_trigger_operations = { |
1010 | .write = write_sysrq_trigger, |
1011 | .llseek = noop_llseek, |
1012 | }; |
1013 | |
1014 | static void sysrq_init_procfs(void) |
1015 | { |
1016 | if (!proc_create("sysrq-trigger", S_IWUSR, NULL, |
1017 | &proc_sysrq_trigger_operations)) |
1018 | pr_err("Failed to register proc interface\n"); |
1019 | } |
1020 | |
1021 | #else |
1022 | |
1023 | static inline void sysrq_init_procfs(void) |
1024 | { |
1025 | } |
1026 | |
1027 | #endif /* CONFIG_PROC_FS */ |
1028 | |
1029 | static int __init sysrq_init(void) |
1030 | { |
1031 | sysrq_init_procfs(); |
1032 | |
1033 | if (sysrq_on()) |
1034 | sysrq_register_handler(); |
1035 | |
1036 | return 0; |
1037 | } |
1038 | module_init(sysrq_init); |
1039 |
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